US supreme court justice Antonin Scalia, in 2000; if one of the new laws imposing random drug-testing on welfare recipients is appealed to the supreme court, Scalia's judgment may prove pivotal. Photograph: AP Photo/Travis Spradling

Florida Governor Rick Scott is poised to fulfill a "top priority" campaign pledge and sign legislation requiring the state's approximately 58,000 welfare recipients to pay for their own random drug tests.

Thirty states took up bills to mandate drug testing for "the welfare people" during the 2011 legislative session, which is now in most states drawing to a merciful close: legislators were otherwise busy restricting abortion, worker and immigrant rights, while liberalising the right to bear arms on college campuses and destroy the environment; Florida and Texas have passed legislation making it harder for people to vote. Democratic Missouri Governor Jay Nixon is considering whether to sign a similar drug-testing bill, though it passed with more than sufficient votes to override a veto.

The drug tests are proposed despite the fact that welfare recipients use drugs at the same rate as the general public. And, thanks to the 1996 welfare reform law passed by President Clinton and congressional Republicans, there aren't even that many people left on welfare to beat up on. "Ending welfare as we knew it" created Temporary Assistance for Needy Families (TANF), pushing mothers from public assistance to McDonalds-wage jobs – if they were lucky. One in five landed with nothing at all, and that was before the recession hit.

The "welfare queen", conservative anti-hero of late 20th-century America, is back. The Republicans and Democrats who nearly eliminated welfare in the 1990s are savagely exploiting those who remain dependent on government assistance for their own benefit. Though bashing poor people on welfare is not serious policy, it makes for good political theatre: first time as tragedy, second time as farce. As Kaaryn Gustafson, professor at the University of Connecticut school of law and an expert on the history of welfare politics, told me:

"The poor often end up being targeted when the economy is bad. I think the drug-testing policies are an expression of economic frustration, resentment toward the poor, and a denial of the policies and structural causes that have caused the welfare rolls to increase again."

A 2004 study by researchers at Penn State, the University of Michigan and the University of Chicago criticised the focus on drug use, finding that "while substance use, abuse and dependence are barriers to self-sufficiency, so are poor education, lack of transportation, physical and mental health problems, and many other difficulties that are more common than substance abuse among welfare recipients."

Not to mention the obliteration of living-wage working-class jobs.

The move to subject people on welfare to drug tests is motivated by the powerful idea that it is poor people's own fault that they are poor. The same goes for welfare reform (people are on welfare because "they don't want to work"), and bans on welfare, food stamps and public housing for those convicted of drug crimes. And it's often pretty straightforwardly racist, too, as when born-again monogamist and rapidly imploding presidential candidate Newt Gingrich called Barack Obama the "food stamp President" (see Joan Walsh on the matter).

Some state legislation gives drug users the opportunity to undergo treatment before they are sanctioned. Others are considering legislation that is purely punitive. The motive is the same, however, whether conservatives pretend to take the "therapeutic" route or not. Louisiana state representative John La Bruzzo, who has also introduced legislation that would pay women on welfare $1,000 get their Fallopian tubes tied, personifies the attitude.

The real story, says Liz Schott, senior fellow with the Centre on Budget and Policy Priorities' welfare reform and income support division, is that welfare reform decimated a social safety net that an increasing number of people need. And worse yet, according to a report she issued last week, cash-strapped states nationwide are now cutting benefits and shortening time limits. The policing of aid recipients is going up as the actual level of aid is plummeting.

Punishing the poor, of course, won't help end poverty. Advocates of welfare drug-testing, like public employee opponents, leverage the bitterness of beat-up private sector workers in 21st-century corporate America in order to make their case. (Florida Republicans, aiming for the trifecta, will also drug test public employees and are considering legislation that would cover those receiving unemployment insurance checks.)

"It resonates with rightwing voters, especially those who work in the private sector, in low-income jobs that require drug-testing," says Gustafson. Unions, in fact, are the one tool private sector workers have – as with so many things – to resist mandatory drug testing, but less than 7% of private sector workers now belong to unions.

This powerful conservative meme first surfaced at the very beginning of the economic crisis. According to the National Conference of State Legislatures, more than 20 states proposed bills in 2009, and 10 did so in 2010. The ACLU is exploring a legal challenge the Florida legislation. Many conservative jurists will support the law: a three-judge panel of the sixth circuit court in the 2003 Michigan case (Marchwinski v Howard) held the law to be constitutional. It was only when the full court split their vote that a lower court ruling against the law was reaffirmed.

If one of these laws gets appealed to the US supreme court, arch-conservative Antonin Scalia will be the justice to watch. Scalia voted with a 5-4 majority that declared it unconstitutional for police to use heat sensors without a warrant to locate pot-growing operations in the 2001 case Kyllo v US. "It's not clear what he would do in a case like this," says Gustafson. "It depends on whether he sees poor people as people, or poor people as wards of the state on par with probationers."

If the courts rule drug testing of welfare recipients to be constitutional, a broad new exception to the fourth amendment will have been carved out. That could lead to testing applicants for student loans or driver's licences. Legal challenges notwithstanding, this legislation stands a good chance of becoming law.

So, if a conservative talks to you about "invasion of privacy", make sure to ask for whom.